Improvement in hot-air furnaces



` a e Manx AfclUsnING, or AURORA, ILLINOIS'.

t :flfMPRovEMNTiN HOTFMR FuRNAcEs.

Specification forming partkof LetterszPatent No. 115,444, datedMay 30, 1871.

Toiall whom it may concern: t i i 'Beit known that fLMARKA; CUSHING, of Aurora, in the countyof Kane and State of Illinois, have invented a new'andusefullmprovement inHeating-Furnace; and lIdo declare that the following is a true andaccurate `description thereof, reference being had to the accompanying drawing and to the letters of reference marked thereon, and being a part of this specification, in whichi Figure lisa vertical section of'my furnace with a ,portionof `the ash-pit broken away to show the pipe `which supplies air to the gasring. Fig. 2 is fa plan ofthe furnace with its top and thatof the combustion-chamber removed. Fig. 8 is a vertical section 'of the exit-pipe. t i i Y Like letters indicate like parts in each iig- UTG. i

The nature ofthis invention relates to an improved construction of airheatin g furnaces,-

whereby more perfect combustion and an increased radiating-surface a-re securedwithin a small compa-ss. Theinvention consists in the peculiar construction of a radiating-chamber for the reception of the heated products of combustion, in connection with thecombustion-chamber and the sleeve exhaust-pipe patented by me July 6, 1869, and numbered 92,-' t 282, whereby a large radiating-surfaceissecuredpwithin the cylindrical casing ofthe furnace;

Inlthe drawing, A represents the ash-pit, surmounted by a fire-pot, B, the upper part of which forms a combustion-chamber, B', closed at the top. 0 is a chute through whichV the ,i fuel is supplied to the fire-pot. D is an annular channel encircling the fire-pot at the plane of the lower side ofthe feed-chute, andis prforated `in the usual manner to form a gasring, thenventon of which I disclaim. E is a tubular conduit, tapping said gas-ring at any convenient point, delivering thereto a supply of fresh airtakenfrom" the external atmosphere at ornear the bottom of the furnace, passing up within the outer casing F, whereby the air` delivered by `it is heated in its pas.

sage to the gas-ring, the more readily to ignite the gases of combustion with which it mixes on its introduction to the fire-pot. G is a seg-k ment of a cylinder, formed of fire-clay, prop'- erly molded andA burned,`cr of other refractin g material, resting upon the gasring and extending entirely around the fire-pot, except at the mouth of the chute. 4 Gl is a diaphragm of the same material, resting on the walls of the segment, which are inclined vfrom front to Y sumed products of combustion discharging into it by the flue J leadingfrom the combustion-chamber. The exit-pipe is in twosections, i

K K', the latter being sleeved on the former and operated as a downward extension by theA rod L, as set forth in said Letters Patent. M is another ilue leading from the back of the ash-pit into the radiator, and is provided with a valve for closing it. The bottom plate of the furnace is provided with proper openings for the admission of cold air to the space inclosed by the shell. From the top hot-air pipes convey the heated air to the required points. The fire-pot being supplied with fuel, combustion proceeds in the usual manner,

y heating to a high degree the nre-clay walls G and diaphragm G. A large volume of gases -evolved from the fuel is detained by the diaphragm G', affording a chance to the gas-rin g to' deliver to it a supply of oxygen, which, being hea-ted in its passage through the conduit E, readily mixes with the gases ofcombustion and ignites them, the ignition being rapid and the combustion perfect, by means of the great heat radiated from the fire-clay walls and dia! phragin.

It is a well-settled principle in calorics that, to insure rapid and perfect combustion,

the supply of oxygen to the gases should be heated before its delivery thereto; hence the importance ofthe conduit E.

The heated currents pass from the combus tion-chamber through the flue J into Athe radiating-chamber H, whence their outflow and the rate of combustion may be,` regulated by FFIHCE raising or lowering the sleeve ofthe exit-tine.

' The lower the mouth of the sleeve is the slower the combustion will proceedybutpwith a constantly-increasing ratio of economy, as, in obedience to natural laws, the heat discharged into the radiating-chamber rises as it enters, and must completely fill it before finding an exit at the bottom of the chamber. Being thus detainedin the chamber, its thin walls readily transmit, by radiation, the heat to the atmosphere passing up through the furnace in Contact with the exterior ofthe radiators. The tubes l a'ord an additional radiating-surtace, but are not essential. The sleeve of the exit-pipe is provided with several openings, of such area that when the sleeve is lowered to the bottom of the radia ytor there will pass up a current of heat in vol ume suiieient to maintain draft enough for combustion and to carry off the unconsumed the casing F, of the ash-pit A, fire-pot B, lue

J, and crescentshaped radiator I-l', having; a. sleeved or extensible exit-pipe K, and with or without the air-pipes I, substantially as described, and for the purpose specified.

MARK A. OUSHING.

Witnesses:

F. G. BRADLEY, Anson' B. JENKS. 

